mail-mx-1.RIPE.NET has no CNAME records.
Question and response
Question
dig mail-mx-1.RIPE.NET. NS
Answer
The response has no answer records.
Authority
ripe.net. 2490 SOA manus.authdns.ripe.net. dns.ripe.net. 1771631722 3600 600 864000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0